Patschan Daniel, Krupincza Krystina, Patschan Susann, Zhang Zhongtao, Hamby Carl, Goligorsky Michael S
Department of Medicine, New York Medical College BSB, R-C21, Valhalla, NY 10595, USA.
Am J Physiol Renal Physiol. 2006 Jul;291(1):F176-85. doi: 10.1152/ajprenal.00454.2005. Epub 2006 Feb 14.
Endothelial progenitor cells (EPCs) have been shown to participate in tissue repair under diverse physiological and pathological conditions. It is unknown whether EPCs are mobilized in response to acute renal injury. The aim of this study was to characterize EPC mobilization and homing in the course of acute renal ischemia. Mice were subjected to unilateral renal artery clamping (UC) for 25 min. At 10 min, 3, 6, 24 h, and 7 days after UC, the pool of circulating and splenic CD34+/Flk-1+ cells within the monocytic population was detected by flow cytometry. For ischemic preconditioning (IPC), the first UC was performed 7 days before the repeated ischemic episode. For EPC detection in the kidney, cryosections were stained for c-Kit+/Tie-2+ cells. The number of circulating EPCs was not significantly affected at any time after UC compared with sham-operated or control mice. IPC did not significantly change the circulating pool of EPCs. Splenectomy performed before UC resulted in a surge of circulating EPCs. Accordingly, splenic EPCs were significantly increased after UC at 3 and 6 h, but not at later times. EPC homing to the spleen was absent in IPC animals. Immunohistochemical analysis of the kidneys showed a sixfold increase in the number of c-Kit+/Tie-2+ cells localized in the medullopapillary region in mice by day 7 after ischemia. Enriched population of c-Kit+/Tie-2+ cells from the medullopapillary parenchyma of Tie-2green fluorescent protein chimeric mice subjected to IPC was isolated and transplanted to wild-type mice with acute renal ischemia. This procedure resulted in the improvement of renal function in recipients. In conclusion, 1) renal ischemia rapidly (within 3-6 h) mobilizes EPCs, which transiently home to the spleen, acting as a temporary reservoir of mobilized EPCs; 2) the late phase of IPC is associated with the mobilization of the splenic pool and accumulation of EPCs in the renal medullopapillary region; and 3) transplantation of EPC-enriched cells from the medullopapillary parenchyma afforded partial renoprotection after renal ischemia, suggesting the role of the recruited EPCs in the functional rescue.
内皮祖细胞（EPCs）已被证明在多种生理和病理条件下参与组织修复。目前尚不清楚EPCs是否会因急性肾损伤而被动员。本研究的目的是明确急性肾缺血过程中EPCs的动员和归巢特征。将小鼠单侧肾动脉夹闭（UC）25分钟。在UC后10分钟、3小时、6小时、24小时和7天，通过流式细胞术检测单核细胞群体中循环和脾脏CD34+/Flk-1+细胞池。对于缺血预处理（IPC），在重复缺血发作前7天进行第一次UC。为了检测肾脏中的EPCs，对冰冻切片进行c-Kit+/Tie-2+细胞染色。与假手术或对照小鼠相比，UC后任何时间循环EPCs的数量均未受到显著影响。IPC并未显著改变EPCs的循环池。UC前进行脾切除术导致循环EPCs激增。因此，UC后3小时和6小时脾脏EPCs显著增加，但在随后时间未增加。IPC动物中不存在EPCs归巢至脾脏的情况。对肾脏的免疫组织化学分析显示，缺血后7天，小鼠髓质乳头区域定位的c-Kit+/Tie-2+细胞数量增加了六倍。从接受IPC的Tie-2绿色荧光蛋白嵌合小鼠的髓质乳头实质中分离出富集的c-Kit+/Tie-2+细胞群体，并将其移植到患有急性肾缺血的野生型小鼠中。该操作导致受体肾功能得到改善。总之，1）肾缺血迅速（3 - 6小时内）动员EPCs，其短暂归巢至脾脏，作为动员的EPCs的临时储存库；2）IPC后期与脾脏池的动员以及EPCs在肾髓质乳头区域的积聚有关；3）从髓质乳头实质移植富集EPCs的细胞在肾缺血后提供了部分肾脏保护作用，提示募集的EPCs在功能挽救中的作用。
